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In the physical sciences, a phase is a region of material that is chemically uniform, physically distinct, and (often) mechanically separable. In a system consisting of ice and water in a glass jar, the ice cubes are one phase, the water is a second phase, and the humid air is a third phase over the ice and water.
The atom-molar heat capacity of a polyatomic gas approaches that of a solid as the number n of atoms per molecule increases. As in the case f gases, some of the vibration modes will be "frozen out" at low temperatures, especially in solids with light and tightly bound atoms, causing the atom-molar heat capacity to be less than this theoretical ...
Vaterite, like aragonite, is a metastable phase of calcium carbonate at ambient conditions at the surface of the Earth. As it is less stable than either calcite, the most stable polymorph, [ 5 ] or aragonite, vaterite has a higher solubility than either of these phases.
The properties of ice II were first described and recorded by Gustav Heinrich Johann Apollon Tammann in 1900 during his experiments with ice under high pressure and low temperatures. Having produced ice III, Tammann then tried condensing the ice at a temperature between −70 and −80 °C (203 and 193 K; −94 and −112 °F) under 200 MPa ...
Calcium carbonate is used in the production of calcium oxide as well as toothpaste and has seen a resurgence as a food preservative and color retainer, when used in or with products such as organic apples. [58] Calcium carbonate is used therapeutically as phosphate binder in patients on maintenance haemodialysis. It is the most common form of ...
Calcium oxide is usually made by the thermal decomposition of materials, such as limestone or seashells, that contain calcium carbonate (CaCO 3; mineral calcite) in a lime kiln. This is accomplished by heating the material to above 825 °C (1,517 °F), [ 6 ] [ 7 ] a process called calcination or lime-burning , to liberate a molecule of carbon ...
During a phase transition of a given medium, certain properties of the medium change as a result of the change of external conditions, such as temperature or pressure. This can be a discontinuous change; for example, a liquid may become gas upon heating to its boiling point, resulting in an abrupt change in volume. The identification of the ...
Aragonite is the high pressure polymorph of calcium carbonate. As such, it occurs in high pressure metamorphic rocks such as those formed at subduction zones. [13] Aragonite forms naturally in almost all mollusk shells, and as the calcareous endoskeleton of warm- and cold-water corals (Scleractinia). Several serpulids have aragonitic tubes. [14]